Method and device for casting metal close to final dimensions

ABSTRACT

A method and a device for the casting of rectangular billets from metal, in particular from steel, close to final dimensions, and for the subsequent inline rolling out of the billet, with a material supply vessel, via the outlet nozzle of which the liquid metal is deposited onto the upper strand of a conveyor belt, on which it solidifies and is transferred to a roll stand for forming, characterized by the following steps: 
     a) before the start of casting 
     aa) the point at which the liquid metal is deposited onto the conveyor belt is predetermined approximately, 
     ab) the conveying speed of the conveyor belt is set as a function of the desired rolling thickness and rolling speed of the roll stand, 
     b) during casting 
     ba) the position of thorough solidification of the metal billet located on the conveyor belt is detected, 
     bb) the temperature of the rolling stock is detected in the region of the roll stand, and 
     bc) the position of thorough solidification and the temperature of the rolling stock are used as control variables for the current position of the point at which the liquid metal leaving the material supply vessel is deposited onto the conveyor belt.

This application is A 371 of PCT/DE99/00891 filed Mar. 13, 1999.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to a method for the casting of rectangular billetsfrom metal, in particular from steel, close to final dimensions and forthe subsequent inline rolling out of the billet, with a material supplyvessel, via the outlet nozzle of which the liquid metal is depositedonto the upper strand of a conveyor belt, on which it solidifies and istransferred to a roll stand for forming. The invention further relatesto a corresponding device for carrying out the method.

2. Discussion of the Prior Art

Stahl und Eisen [Steel and Iron] 1986, page 65ff., discloses a methodwith a traveling mold for casting close to final dimensions, in whichthe steel is cast onto casting carriages moving horizontally. Thecasting carriages run on a rail, and at the end of the mold section thebillet is transferred to a roller table, and the billet must havethoroughly solidified at the latest when it enters the first roll standarranged downstream. This publication specifies the relationship betweenthe casting speed and the effective mold length. There is no suggestionin this publication of changing the position of the material supplyvessel during operation.

German reference DE 43 44 953 C2 discloses a method for casting a metalstrip close to final dimensions on a belt-type casting device providedwith a melt receiving vessel and with a conveyor belt, which listsmethod instructions and means for exerting influence on the spread ofthe metal melt on the conveyor belt. The arrangement of the castingvessel in relation to the conveyor belt cannot be changed in this case.

SUMMARY OF THE INVENTION

The object of the invention is to provide a method and a correspondingdevice in which simple design means ensure casting close to finaldimensions and subsequent rolling of rectangular billets of high anduniform quality at any desired casting speed and with any desired billetthicknesses.

According to the invention, before the start of casting, the materialsupply vessel is set in a predeterminable position with respect to thelongitudinal extent of the conveyor belt and therefore the point atwhich the liquid metal is deposited onto the conveyor belt ispredetermined approximately. Furthermore, the conveying speed of theconveyor belt is set as a function of the desired rolling thickness androlling speed of the roll stand. During operation, the position forthorough solidification and the temperature of the rolling stock arethen used as control variables for the current position of the point atwhich the liquid material leaving the material supply vessel isdeposited onto the conveyor belt.

The variable depositing of the melt onto the conveyor belt affords asimple and highly effective possibility for setting the mean temperatureof the cast strip both at the end of the conveyor belt and at entry intothe roll stand. In this case, the mean temperature comprises the averageof the permissible temperature differences over the strip cross sectionof the cast strip.

The variable depositing point of the melt, specifically both approximatesetting and the fine setting which is carried out during operation,makes it possible to set a special inlet temperature profile of thebillet at entry into the rolling mill.

In addition to influence being exerted on the current position of thepoint at which the liquid metal leaving the material supply vessel isdeposited onto the conveyor belt, further regulating subsystems are alsoadvantageously used. Thus, it is proposed to detect the thickness of thematerial billet located on the conveyor belt and use said thickness forcontrolling the quantity flow of the liquid material leaving thematerial supply vessel. In a further advantageous procedure, the speedof the conveyor belt is detected and is used to control the quantityflow of the liquid material leaving the material supply vessel.Furthermore, the geodetic height of the metal located in the materialsupply vessel may be taken into account in the control of the quantityflow.

Moreover, in order to control the position of the material depositingpoint, it is proposed to take into account the discharge of heat fromthe metal billet located on the conveyor belt.

For carrying out the method, the material supply vessel has movementelements, by means of which it is capable of being moved horizontally,and at the same time coaxially to the major axis of the conveyor belt,in or opposite to the conveying direction of the billet. Furthermore,the material supply vessel is connected to an actuator which, forregulating purposes, is connected to a regulating means taking intoaccount the thorough solidification of the billet and the temperature ofthe rolling stock and by means of which the position of the materialsupply vessel can be set as desired.

In an advantageous embodiment, the material supply vessel is equippedwith wheels which run on rails. It is proposed, furthermore, to usesliding elements which match with a track.

In another advantageous embodiment, the movement elements are a thrustmechanism which is designed such that the mouth of the outlet nozzle ofthe material supply vessel can be guided at a constant distance from theupper strand of the conveyor belt over a defined region considered to besufficient.

In another embodiment, piston/cylinder units are used, which areconnected to a regulating means in such a way that, in the event of ahorizontal movement of the material supply vessel, the mouth of thelatter can be guided at a constant distance from the upper strand of theconveyor belt. In this case, the piston/cylinder units form the supportswhich are mounted at the corners of the material supply vessel.

A hydraulic piston/cylinder unit is proposed as an advantageousembodiment of an actuator for changing the horizontal position of thematerial supply vessel. In one embodiment, a piston/cylinder unit isprovided, which is designed as a synchronous cylinder, one end of whichis connected to the material supply vessel by a spacer rod.

In another advantageous embodiment, it is proposed that the positionactuator be an electric drive which is connected to the material supplyvessel by an endless belt.

It is proposed, furthermore, to arrange the position actuator and thematerial supply vessel on a stand and, in this case, to use the actuatorfor fine tuning and the stand, which has its own drive, for theapproximate positioning of the material supply vessel.

Various forms of construction are proposed for the material supplyvessel. In one embodiment, the material supply vessel is preceded by aladle which is provided with a stopper rod or with a slide and whichcontrols the inflow of the liquid metal. In another embodiment, thematerial supply vessel is designed as a vacuum vessel having a chargingchamber, into which the melt is introduced.

In order to achieve reliably the desired material properties and theintended inlet temperature profile, in one embodiment of the invention ahousing is provided which encases at least the free surfaces of thebillet from the point at which the liquid metal is deposited onto theconveyor belt and during transport by the latter. This housing possessesa cover which is designed as a blind. This blind is connected at one endto the outlet nozzle of the material supply vessel and at the other endpossesses a winding device. This housing is connected to a gas supplymeans, via which, in particular, inert gas is conveyed into the freespace.

BRIEF DESCRIPTION OF THE DRAWINGS

An example of the invention is presented in the accompanying drawing inwhich:

FIG. 1 shows a device for casting close to final dimensions, includingthe regulating means;

FIG. 2 shows the embodiment of the material supply vessel as a vacuumvessel; and

FIG. 3 shows a strip casting device with a housing.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1 shows a material supply vessel 11, via the outlet nozzle 13 ofwhich liquid metal M is supplied to a conveyor belt 31. The materialsupply vessel 11 is capable of being moved in the direction of the majoraxis I of the conveyor belt 31 via movement elements 22, these being, inthe present case, wheels 14 which run on a rail 23. In this case, thematerial supply vessel is moved horizontally in the direction of themajor axis I of the conveyor belt 31 by an actuator 21 via a spacer rod16.

In order to supply the liquid metal M into the material supply vessel11, a ladle 66 is provided, which possesses a dip spout 67 capable ofbeing closed at the head end by means of a stopper rod 63.

The conveyor belt 31, which possesses an upper strand 32 and a lowerstrand 33, is driven by a drive 34. On the upper strand 32, the liquidmetal M solidifies to form the billet S and is supplied to a roll stand91. This roll stand is driven by a roll drive 92 which rolls out thebillet S to the desired thickness of the rolling stock W and finallywinds it up in a winding means 93.

The device for the casting of rectangular billets from metal close tofinal dimensions is equipped with a series of measuring elements,specifically with a measuring element 51 for detecting the thoroughsolidification of the billet S and with a measuring element 52 fordetecting the temperature of the rolling stock W.

A measuring element 53 for detecting the speed is provided on the drive34 of the conveyor belt 31.

A measuring element 54 for detecting the geodetic height of the liquidmetal M is arranged in the material supply vessel 11.

A measuring element 55 for detecting the thickness of the metal billetis arranged above the upper strand 32 of the conveyor belt 31 in thevicinity of the outlet nozzle 13 of the material supply vessel 11.

A measuring element 56 for detecting the discharge of heat from thebillet S is provided in the vicinity of the roll stand 91 and upstreamof the latter in the billet conveying direction.

A measuring element 58 for detecting the thickness of the rolling stockW is arranged downstream of the roll stand 91 in the conveying directionof the billet.

The measuring element 51 for detecting thorough solidification and themeasuring element 52 for detecting the temperature of the rolling stockare connected to a regulating means 41 which is connected for controlpurposes to the actuator 21 for setting the position of the materialsupply vessel 11.

The measuring element 53 for detecting the speed of the conveyor belt isconnected to a regulating means 43, the measuring element 54 fordetecting the geodetic height is connected to a regulating means 44 andthe measuring element 55 for detecting the thickness of the metal billetis connected to a regulating means 45, the regulating means 43-45 beingconnected to an element 61 for controlling the quantity of liquid metalM.

The measuring element 56 for detecting the heat discharge is connectedto a regulating means 46, the measuring element 57 for detecting thespeed of the roll stand is connected to a regulating means 47 and themeasuring element 58 for detecting the thickness of the rolling stock isconnected to a regulating means 48, the regulating means 46-48 beinglinked to the regulating means 41. At the same time, the (main)regulating means 41 relies essentially on the measurement values fromthe measuring elements 51-52 and, in addition, on those from themeasuring elements 56-58.

FIG. 2 shows a material supply vessel 11 designed as a vacuum vesselwhich is connected to a vacuum device 65. This material supply vesselpossesses a charging chamber 12, into which a dip spout 67 projects. Thedip spout 67 is capable of being closed by means of a closing element 62which is designed here as a slide 64. The dip spout 67 is arranged inthe bottom of a ladle 66 in which liquid metal M is located.

The material supply vessel is supported on movement elements 22 whichare designed here as piston/cylinder units 27. These piston/cylinderunits 27, which are connected for regulating purposes to a regulatingmeans 49, are capable of maintaining the outlet nozzle 13 at a constantdistance from the upper strand 33 during a movement of the materialsupply vessel in the direction of the major axis I of the conveyor belt31.

The material supply vessel 11 is connected via a spacer rod 16 to anactuator 21 which is designed here as a piston/cylinder unit 28.

The actuator 21 for fine tuning and the movement elements 22 arearranged, in the present case, on a stand 18 which is capable of beingmoved on a rail 23 via wheels 14. In order to set the position, inparticular the approximate position, of the material supply vessel 11,at least one of the wheels 14 is connected to a further actuator 21.

In FIG. 3, the movement elements 22 are designed as sliding elements 15which are fastened to the material supply vessel 11 and which match witha track 24.

Provided on the material supply vessel 11 are levers 25 having joints26, by means of which the position of the outlet nozzle 13 in relationto the upper strand 33 of the conveyor belt 31 can be set as desired.

In the present case, the material supply vessel 11 is connected via anendless belt 17 connected to an actuator 21 which is designed here as anelectric drive 29.

Furthermore, the billet S is encased by a housing 71 which is connectedto a gas supply 81. The housing 71 possesses a cover 72 which, in thepresent case, is designed as a blind 73. The blind 73 is fastened,gastight, at one end to the material supply vessel 11 and at the otherend has winding devices 74. Preferably inert gas is conveyed into theinterior 75 of the housing 71 via the gas supply 81.

I claim:
 1. A method for casting rectangular billets from metal close tofinal dimensions and for subsequent inline rolling out of the billet,with a material supply vessel, via an outlet nozzle of which the liquidmetal is deposited onto an upper stand of a conveyor belt, on which themetal solidifies and is transferred to a roll stand for forming arolling stock, the method comprising the steps of: a) before startingcasting, aa) approximating a point at which the liquid metal isdeposited onto the conveyor belt, and ab) setting conveying speed of theconveyor belt as a function of a desired rolling thickness and rollingspeed of the roll stand; and b) during casting, ba) detecting positionof thorough solidification of the metal billet located on the conveyorbelt, bb) detecting temperature of the rolling stock in a region of theroll stand, and bc) using the position of thorough solidification andthe temperature of the rolling stock as control variables for thecurrent position of a point at which the liquid metal leaving thematerial supply vessel is deposited onto the conveyor belt.
 2. A methodas defined in claim 1, including detecting a thickness of the metalbillet located on the conveyor belt and using the detected thickness forcontrolling a quantity flow of the liquid metal leaving the materialsupply vessel.
 3. A method as defined in claim 1, including detectingspeed of the conveyor belt and using the detected speed for controllinga quantity flow of the liquid metal leaving the material supply vessel.4. A method as defined in claim 1, including taking geodetic height ofthe metal located in the material supply vessel into account whencontrolling the quantity flow of the liquid metal leaving the materialsupply vessel.
 5. A method as defined in claim 1, including taking adischarge of heat from the metal billet located on the conveyor beltinto account when controlling the position of the material depositingpoint.
 6. A device for casting rectangular billets from metal close tofinal dimensions and for subsequent inline rolling out of the billet,comprising: a metal supply vessel having an outlet nozzle; ahorizontally arranged conveyor belt; at least one roll stand downstreamof the conveyor belt for forming a rolling stock; movement elementsconnected to the material supply vessel so as to move the supply vesselin a horizontal direction, coaxially to a major axis of the conveyorbelt, in or opposite to a conveying direction of a billet; an actuatorconnected to the material supply vessel; regulating means for regulatingthe actuator; first measuring elements connected to the regulating meansand operatively arranged for detecting a position of the thoroughsolidification of the billet; and second measuring elements connected tothe regulating means and operatively arranged for detecting temperatureof the rolling stock.
 7. A device as defined in claim 6, and furthercomprising means for controlling quantity flow of metal through theoutlet nozzle of the metal supply vessel.
 8. A device defined in claim7, wherein the control means includes at least one of a controllableclosing element and a vacuum device.
 9. A device as defined in claim 6,and further comprising rails, the movement elements being wheels whichare connected to the material supply vessel and run on the rails.
 10. Adevice as defined in claim 6, and further comprising a track, themovement elements being sliding elements which are connected to thematerial supply vessel and match with the track.
 11. A device as definedin claim 6, wherein the movement element are levers which have jointsand are designed as thrust mechanisms such that, in the event of ahorizontal movement of the material supply vessel, a mouth of the outletnozzle is guided at a constant distance from an upper strand of theconveyor belt over a defined region.
 12. A device as defined in claim 6,wherein the movement elements are piston/cylinder units, and furthercomprising further regulating means connected to the piston/cylinderunits for guiding a mouth of the outlet nozzle at a constant distancefrom an upper strand of the conveyor belt in the event of a horizontalmovement of the material supply vessel.
 13. A device as defined in claim6, wherein the actuator is a hydraulic piston/cylinder unit.
 14. Adevice as defined in claim 13, wherein the piston/cylinder unit is asynchronous cylinder, and further comprising a spacer rod arranged toconnect the synchronous cylinder to the material supply vessel.
 15. Adevice as defined in claim 6, wherein the actuator includes an electricdrive, and an endless belt that connects the electric drive to thematerial supply vessel.
 16. A device as defined in claim 6, and furthercomprising an additional stand having its own drive for moving coaxiallyto the major axis of the conveyor belt, the movement elements beingarranged on the additional stand.
 17. A device as defined in claim 6,wherein the material supply vessel is a vacuum vessel having a chargingchamber into which the melt can be introduced.
 18. A device as definedin claim 6, and further comprising a housing arranged to encase at leastfree surfaces of the billet from a depositing point on the conveyor beltand during transport by the conveyor belt.
 19. A device as defined inclaim 18, wherein the housing has a cover equipped as a blind which isconnected at one end to the outlet nozzle of the material supply vesseland allows it to execute an unimpeded traveling movement, and furthercomprising a winding device connected at an other end of the cover. 20.A device as defined in claim 18, and further comprising gas supply meansconnected to the housing for supplying gas.